Missile simulator



Feb. 14, 1961 w. E. THORNTON MISSILE SIMULATOR 4 Sheets-Sheet 1 Filed July 15, 1957 Feb. 14, 1961 w. E. THORNTON mssxua: SIMULATOR Filed July 15, 1957 4 Sheets-Sheet 2 n 7 4 r w x M. w MM Feb- 14, 1961 w. E. THORNTON 2,971,274

MISSILE SIMULATOR Filed July 15, 1957 4 Sheets-Sheet 3 5 l z /ane Feb. 14, 1961 w. E. THORNTON 2,971,

} MISSILE SIMULATOR Filed July 15, 1957 4 Sheets-Sheet 4 United States Patent MISSILE SIMULATOR William Edgar Thornton, Los Angeles, Calif., assignor to Del Mar Engineering Laboratories, Los Angeles, -Calif., a corporation Filed July 15, 1957, Ser. No. 672,058

7 Claims. (Cl. 35-25) This invention is directed generally to a system for recording simulated data corresponding to a missile in flight. More particularly, the invention is concerned with a system for photographically recording a target and the flight path of a simulated missile fired at the target.

Serious problems have arisen in recent years in training the crews of fighter aircraft. Problems have also arisen in evaluating the fire control efficiency of aircraft, insofar as missile firing is concerned.

Even when missiles are actually fired at airborne targets, problems have been encountered in the prior art in providing some means for measuring the miss-distances between the missiles and the target. Only with such measurements can the efiectiveness of the fire control system of the attacking aircraft be properly evaluated, and the capabilities of the crews operating the system be determined.

The problems of measuring such miss-distances have been solved to a large extent by the system disclosed and claimed in copending application Serial No. 610,140, filed September 17, 1956 in the name of William E. Thornton. In the system of the copending application, radar-optical means are used to obtain a photographic recording of the miss-distances of one or more missiles fired at an airborne target.

The system of the copending application fulfills its intended purpose with a high degree of efiiciency, and it solves the pressing problem of providing a visual scoring system for missile firing. However, the scoring system of the copending application requires that missiles be actually fired at the target from the attacking aircraft.

The high cost of missiles, and the necessity that they be fired only in uninhabited places, has greatly restricted training programs. Other important programs, which normally require the firing of missiles, have also been seriously curtailed because of these factors.

The present invention provides a system which enables an accurate replica of a missile in flight to be displayed and recorded without the need actually to fire a missile. The invention provides that all the necessary data concerning the flight of the missile, and its miss-distance with respect to the target at which it is fired, be provided to correspond exactly to the data normally related to an actually fired missile.

The simulated missile firing system of the invention requires relatively few components, and it conveniently adapts itself for mounting in an aircraft. This enables training flights to be made over areas that are not completely uninhabited and without the concomitant loss of expensive missiles. The system, therefore, enables an accurate evaluation to be made of the crew and fire control apparatus of the aircraft on a most convenient basis.

In the simulated missile firing system of the invention,

a motion picture camera is mounted in the attacking aircraft, and the optical axis of this camera is directed at the target area. The camera, therefore, records in a series of optical image frames on its film strip successive images showing the path of the airborne target.

The cathode-ray beam of a cathode ray tube is actuated by apparatus which, in turn, is under the control of various analogue generators and computers. The cathode-ray beam is controlled in accordance with the path a missile would have traveled if one had actually been fired by the fire control system. The luminous spot formed by the beam as it impinges the viewing screen of the cathode-ray tube moves across the viewing screen to represent the path of the missile. Suitable means are provided for projecting images of the luminous spot onto the film strip in superimposed relationship with the images of the target.

The film strip records, therefore, images of the moving airborne target, and it also records images of a spot moving towards the target and representing a simulated missile fired at the target. The relative ranges of the missile and the target are also indicated on the film strip. This enables a determination to be made of the actual optical image frame of the film at which the simulated missile crosses the path of the target. The actual missdistance between the simulated missile and the target can then be accurately measured.

In a manner to be more fully described, the system of the invention produces a luminous spot on the screen of a cathode ray tube, the path of which is the exact replica of the path a missile would have taken, if a missile had actually been fired by hte aircraft under the conditions existing at the simulated firing point. Images of this spot are then super-imposed on images of the target area, and the superimposed images are recorded on a motion picture film strip to obtain a record of the relative path of the target and of the simulated missile.

Other significant features and details of the present invention will become apparent from the following description, particularly when the description is taken in conjunction with the accompanying drawings. These drawings are intended to be merely illustrative of an embodiment of the invention.

In the drawings:

Figure 1 shows a fighter aircraft having an access panel positioned at its forward end between the cockpit and the nose of the aircraft, which panel supports a blister, which, in turn serves as a convenient mounting means for the apparatus constituting an embodiment. of the system of the present invention;

Figure 2 is a detailed view, partly in section, of a modified camera-oscilloscope assembly which is used in the system of the invention and which records images of the path of the airborne target on successive frames of a film strip, and which also is constructed to superimpose on the film strip images of a luminous spot displayed on the screen of a cathode ray tube to represent the path of a simulated missile in flight;

Figure 3 is a perspective view of the camera-oscilloscope of Figure 2 for providing the superimposed film record in a maner to be described;

Figure 4 is a fragment of a film strip bearing composite visual images of the oscilloscope cathode ray tube spot indications superimposed on the target images, and which film strip indicates the characteristics of the flight path of a simulated missile;

Figure 4a is an enlarged representation of a particular optical image frame of the film strip of Figure 4;

Figires 5 and 5a are vector diagrams useful in explaining the principles upon which the system of the present invention is predicated; and

Figure 6 is a block diagram of a control system which is used to correlate information regarding the flight conditions of the aircraft and of the simulated missile, and for integrating such information on the viewing screen of a pair of cathode-ray tubes so that corresponding indications may be made on the film strip of Figure 4.

The aircraft of Figure 1 is indicated at 10, and it has a usual access panel 12. This panel is mounted on the top of the aircraft just forward of the cockpit. In accordance with one embodiment of the invention, the various components of the apparatus used in the system of the invention may be conveniently mounted within a blister 14 which is mounted on the access panel. Of course, and as will be evident as the description proceeds, the apparatus may be mounted at any other convenient position in the aircraft.

As shown, for example, in Figures 2 and 3, the apparatus of the invention includes a motion picture camera 22. This camera may, for example, be of the usual 35 millimeter type, having a 4-inch lens and a film speed of frames a second. The camera is equipped with a combining lens 2.4 which will be described in detail.

The camera 22 is mounted in the blister 14 of Figure 1 by any suitable mounting means (not shown), and it is positioned so that its lens 24 is directed upwardly to an appropriate mirror element (not shown) mounted in a cowl 28 (Figure 1) formed in the blister. is positioned to direct optical images of the field of view from the front of the aircraft to the lens 24 of the camera. In general, the optical axis of the camera is directed by reflection substantially along the longitudinal axis of the aircraft.

Figures 2 and 3 show the mechanical details of the motion picture camera 22, of the combining lens 24 and of a pair of associated cathode-ray tubes 39 and 31. These figures also show a convenient means by which these components may be supported in assembled relation with respect to one another for mounting in the blister 14, or in any other suitable position in the aircraft. The camera 22 may be actuated by any suitable and usual electric drive mechanism. The camera operates in known manner to draw a film strip 50 in intermittent fashion from a reel 54 past a conventional shutter assembly 52 to a reel 56. I

The lens system 24 includes a first section which constitutes a normal objective lens for the camera. This first section may include, for example, a pair of convex lenses 57 and 58. These lenses are mounted in a usual lens barrel 60, and they are spaced axially along this barrel. The lenses 57 and 58 are constructed to focus optical images on the film strip 50 in successive image frames along the strip. An aperture stop 62 is positioned be: tween the lenses 57 and 58 in the lens barrel 6! The relative aperture of the first section of the lens system 24 may, for example, be f/ 8. The optical images introduced to the film strip of this system are represented, for example. by the image frames on the fragment of the film strip 50 in Figure 4. i The lens system 24 also includes a second section for directing images from the viewing screen of the cathoderay tube 39 to the film strip 50. These latter indications appear as luminous spots on the screen of the oathode-ray tube 30, and images of these spots are directed to the film strip in correlation with the optical image frames.

The second section of the lens system 24 is mounted in a housing 64. This housing is supported on the frame of the camera 22 by means of a bracket 66 (Figure 3). The entire assembly may be supported on the underside of the blister 14 in the access panel 12 of Figure l in the described position by means, for example, of a supporting arm 68. This arm is secured to the camera casing by means of screws 70. The housing 64 also serves to support the cathode-ray tube 39, and this is accomplished by means of a peripheral mounting collar 72. This collar surrounds the cathode-ray tube 34) adjacent its view- This mirror ing screen so that the viewing screen extends into the housing.

The second lens system includes a pair of convex lenses 74 and 76 which are mounted in a lens barrel 78. The lens barrel 78, in turn, is supported within the housing 64 by any suitable means. The two lenses 74 and 76 are spaced axially within the lens barrel 78 along an optical axis which is essentially perpendicular to the optical axis of the first section of the lens system 24. An aperture stop 80 is included in the lens barrel 78 between the lenses '74 and 76.

The cathode-ray tube 30 is mounted on an axis essentially parallel to the optical axis of the first section of the lens system 24 and the tube is positioned with its screen facing the rear of the camera 22. A mirror 82 is mounted within the housing 64 by any appropriate means, not shown. This mirror is positioned to direct images from the screen of the cathode-ray tube 30 along the optical axis of the second section of the lens system 24. These images are directed through the lenses 74 and 76 and through the aperture stop 8d into a compartment 84. The compartment 84 is adjacent the lens barrel of the first section of the lens system. A second mirror 86 is mounted in the compartment 84, and this second mirror is positioned to direct images from the lenses 74 and 76 along a path parallel to the optical axis of the first lens section. a

The second section of the lens system 24 serves to focus on the film strip 50 images of luminous spots or indications appearing on the screen of the cathode-ray tube 30, The aperture stop so is adjusted so that the second lens section has a relative aperture of, for example, N35.

The images of the indications on the screen of the cathode-ray tube 30 extend transversely across the film strip 50 at the top of corresponding ones of the optical image frames in Figure 4. The film strip 50, therefore, carries a continuous record in successive optical image frames of the target which is disposed in the area in front of the aircraft to which the reflected optical axis of the camera is directed; and the film strip also carries a correlated continuous record in successive transverse image frames of luminous indications appearing on the viewing screen of the cathode-ray tube 30.

The lens system 24 also includes a third section for directing images from the screen of the second cathoderay tube 31 to the film strip. These latter indications appear as luminous spots on that viewing screen and images of these spots are directed to corresponding ones of the optical image frames in Figure 4.

The third section of the lens systems 24 is mounted in a housing 65. This housing is supported on the frame of the camera 22 by means of a bracket 67 (Figure 3). This latter section includes a pair of convex lenses 75 and a 77 which are mounted in a usual lens barrel 79. The lens barrel 79, in turn, is supported within the housing 65 in any suitable manner. The two lenses 75 and 77 are spaced axially within the lens barrel 7? along an optical axis which is essentially perpendicular to the optical axis of the first section of the lens system 24. An aperture stop 81 is included in the lens barrel 7% between the lenses 75 and 77.

The cathode-ray tube 31 is mounted on an axis essentially parallel to the optical axis of the lens system 24, and the tube is positioned with its viewing screen facing the rear of the camera 22.

A mirror 82a is mounted within the housing appropriate mounting. This mirror is positioned to direct images from the screen of the cathode-ray tube 31 along the optical axis of the third section of the lens system 24. These images are directed through the lenses 77 and 75 to a dichoric mirror 83. The dichoric mirror 83 is mounted at an inclination within the lens barrel 6i? by any suitable means. This mirror is positioned to direct images of the indications on the screen of the cathoderay tube 31 along the optical axis of the first section of 65 by any the lens system 24. These latter images are directed to the film strip 50. These images are recorded on the film strip in superimposed relation with the optical images in successive frames of the film strip.

The dichoric mirror 83 has the property of reflecting light rays in the blue end of the spectrum and permitting light rays in the remainder of the spectrum to pass through it. Therefore, most of the light rays entering the lens system 24 along the optical axis of the first section of the lens system pass through the mirror element 83 and pass unimpeded to the film strip 5i). Therefore, the images of the target area may be recorded on the film strip 56 in normal manner. However, the mirror 83 serves to reflect images from the lenses 75 and 77 to the film 50 which are predominantly blue. Therefore, the images of the luminous dots appearing on the screen of the cathode-ray tube 31 are superimposed on the images of the target.

As shown in Figure 4a, images T of the target are projected through the first section of the lens system 24, and these images appear in successive optical image frames on the film strip 50. A predominantly blue luminous dot is developed on the screen of the cathoderay tube 31, and the position of this dot on the screen is controlled, as will be explained, in accordance with the flight path of the simulated missile. Images of this blue dot are projected through the lenses 75 and 77, and these images are reflected by the dichoric mirror 83 to the film strip. The images M of the dot appear, therefore, in successive film frames in Figure 4. These images represent the actual path that a missile would take if one had been fired under the firing conditions encountered by the aircraft, and this path is as viewed from the aircraft.

As was the case in the copending application 610,140 referred to above, further information is necessary before the actual miss-distance between the simulated missile and the target can be determined. That is, the

- relative ranges of the target and the simulated missile must be displayed. Then, when these ranges are equal, the simulated missile in effect meets the plane of the target and crosses its path. Then, the optical image frame of the film strip of Figure 4 designating that condition actually represents the miss distance between the simulated missile and the target. This latter data is provided by the cathode-ray tube 30.

The cathode-ray tube 30 is controlled, as will be explained, so that a series of fiducial range markings are developed across its viewing screen. These markings extend vertically and they are spaced from one another by a distance corresponding, for example, to .2 of a mile. The images F of these markings extend across the film strip at the top of the successive frames in Figure 4.

The cathode-ray tube 30 is further controlled to develop an indication representing the distance to the simulated missile from the aircraft, and to develop another indication representing the distance to the target from the aircraft. Images A and B of these respective indications are recorded on the film strip adjacent the range fiducial markings F, as shown in Figure 4. As described in the copending application, because the distance to the target is decreasing as the attacking aircraft approaches, and because the distance to the receding simulated missile is increasing, therefore the images A move effectively on a diagonal path from one frame to the next across the film 50 and from the left hand side of the film to the right hand side in Figure 4. This path may be considered linear for all practical purposes during the short intervals that are considered, and it may be represented by the illustrated dashed line drawn through the A indications.

For the same reason, the images B move effectively in a diagonal path from one frame to the next across the film strip 50 and from the right hand side of the film strip in Figure 4 to its left hand side. This latter path also is linear for all practical purposes during the short intervals that are considered, and the path may be represented by the illustrated dashed line that is drawn through the B images in Figure 4.

The point at which the diagonal path of the A images crosses the diagonal path of the B images represents the optical image frame at which the distance to the target from the aircraft is the same as the distance to the simulated missile. That is, this cross-over point represents the instant that the simulated missile crosses the path of the target. This occurs in the optical image frame of the film strip 50 represented by the arrow in Figure 4. As clearly shown in this figure, the images A and B proceed along their respective diagonal paths from frame to frame, and these images cross in the frame indicated by the arrow.

The selected optical image frame of the :film strip 50 at which the simulated missile crosses the path of the target is shown in Figure 4a. It will be remembered that this is the frame indicated by the arrow in Figure 4. The target image T and the simulated missile image M both appear in the optical image frame of Figure 4a. Also appearing in this frame are the two merged images A and B corresponding to the equal indicated. distances to the simulated missile and to the target. Also appearing are the fiducial range markings F, each corresponding (for example) to .2 of a mile of the indicated distance.

The miss distance components in the image frame of Figure 4a are indicated by the arrows a and e. Scoring is accomplished by scaling the miss distance components a and e shown in the photograph, and by applying appropriate factors as determined by the fiducial range markings Z and the geometry of the optical system. With a 10-inch lens, for example, one optical image frame width is 475 feet for each mile of range. Therefore, if a miss shown is, for example, ten percent of a frame width at two and a half miles range, the actual miss is 119 feet.

With the described indications, therefore, it is possible to determine the actual miss distance of a simulated missile and an airborne target. The ensuing description will describe the manner in which the image M is produced, and how that image is controlled so that the flight path of an actual missile fired under the equivalent conditions may be simulated. Also to be described is the manner in which the range indications A for the simulated missile are obtained; the fiducial range markings F andthe target ranges B being provided by usual radar techniques.

With reference now to the diagrams of Figures 5 and 5a, the point O represents the point at which the simulated missile is fired. At that point, the Y axis is the vertical axis of the aircraft and the Z axis is the horizontal transverse axis of the aircraft. The longitudinal axis of the aircraft is represented by the axis X and the aircraft is proceeding along that axis at the firing point.

Then, the diagram of Figure 5 represents the flight path (F of the missile, the flight path (Ff) of the fighter aircraft, looking into the X, Y plane. In like manner, the diagram of Figure 5a represents the flight path (F of the missile, and the flight path (Ff) of the fighter, looking into the X, Z plane. The independent path (F of the airborne target is illustrated in both these diagrams.

The length of the flight path (F of the missile increases at a rate determined by the simulated speed of the missile. An analogue voltage corresponding to the flight path of the missile is generated (as will be described) by an analogue generator located in the fighter aircraft.

The angle 5 which'the flight path (F of the missile makes with the X-axis in Figure 5 and the angle which that path makes with the X-axis in Figure 5a are determined by the flight characteristics of the equivalent actual missile, and by various monitored flight conditions of the aircraft itself. These latter conditions may, for example, be the angle of attack, air velocity, altitude and yaw of'the aircraft, etc. An analogue voltage repre senting the missile flight path is developed in the aircraft, as will be described, by a suitable analogue generator. Also, voltages representing the monitored conditions are developed in the aircraft from usual transducers monitoring these conditions. The latter voltages are used in a manner to be described to modify the analogue voltage representing theflight path of the missile.

The aircraft carries three gyros for establishing the reference X, Y and Z-axes at the firing point. These gyros are caged until the firing point is reached, and they are then released in known manner. The gyros are mounted in known manner in mutually perpendicular relationship to indicate these respective axes, and so that they'may indicate any departure from these respective axes by the aircraft.

The aircraft itself is assumed to have changed its course at the firing point (O and to be proceeding along the path (P in Figures 5 and 5a. This latter path may change from time to time as the aircraft is maneuvered, it is illustrated as disposed at an angle to the X-axis in Figure 5, and at an angle 0 to the X- axis in Figure a.

The vector representing the path (F of the fighter aircraft can change both in inclination and in the rate at which its length increases. These changes, as noted above, are in correspondence with changes in the course and speed of the aircraft subsequent to the firing of the simulated missile. It is usually necessary for suitable corrections to be made to the indications of the simulated missile path when the aircraft changes course subsequent to the firing point. This is because the aircraft records the optical images along a new optical axis for each change in its course, and the optical images of the target are, in effect, shifted although both the target and the simulated missile effectively continue along their original paths.

The path (F,,) of the target as represented in Figures 5 and 5a is, of course, independent of the aircraft and of the simulated missile.

In accordance with the illustrated embodiment of the invention, the cathode-ray beam of the cathode-ray tube 31 is controlled in a manner to be described in conjunction with Figure 6. This control is such that the movement of the luminous spot produced by the beam on the viewing screen of the cathode-ray tube 31 represents the path of the simulated missile as equated to the vertical and horizontal transverse axes of the aircraft itself, even though the aircraft itself may change its course after the firing point.

As the aircraft is maneuvered to aim the missile at the target transducers on the aircraft develop analogue voltages which, as noted above, respectively are functions of the aircraft conditions such as those enumerated above. These voltages modify the voltage generated by the analogue generator referred to'above, the latter voltage being a function of the acceleration and velocity of the simulated missile.

The modified voltage referred to above is then used in the system of the invention to relate the path of the simulated missile to the vertical and horizontal transverse axes of the aircraft at the firing point. The other control voltages are developed in a manner to be described as the aircraft changes its course. These latter control voltages are used to correct the indicated path .of the simulated missile and relate it to these axes as the position of the aircraft is changed.

The latter control voltages are obtained under the controlof the gyros referred to above. As noted, these gyros are released at the firing point. Suitable trans ducers are coupled to the gyros, and these transducers generate. voltages which represent in an analogue manner '8 any variations in the course of the aircraft from the X, Y and Z axes. The, resulting voltages are utilized effectively to correct the simulated path of the missile in a manner to be described, and to relate that path to the course of the aircraft itself.

The camera 22 in the aircraft continually records images of the target, as taken along an optical axis that changes as the course of the aircraft changes. Therefore, it is evident that compensating changes must be made to the simulated flight of the missile if it is to bear a proper relationship to the recorded optical images of the target itself.

In a time T after the missile has been fired, the aircraft is assumed to have a position O and the missile is assumed to have a position O At the new position O of the aircraft, the simulated missile is displaced from the aircraft along a vector V in the XY plane of Figure 5; and along a vector V in the X2 plane of Figure 5a.

The vector V is displaced at an angle a to the flight path P; of the aircraft at the new position Of in Figure 5. As indicated by the equations in Figure 5:

The values for Y and explained. Also,

Y, may be computed, as will be This angle, therefore, can be determined. It follows then, that the actual value of the V, can be computed.

The displacement of the simulated missile from the aircraft along, for example, the new vertical Y-axis of the aircraft at the new position O of the aircraft is represented .by the Vector D Likewise, the displacement of the missile along, for example, the new horizontal X-axis of the aircraft at the new position O or in the direction of the flight of the aircraft, is represented by the vector D Both the vectors D and D can be computed, the vector D being equal to V sin or and the vector D being equal to V cos 0:.

In like manner the new aircraft Z-axis position dis placement of the simulated missile, which is represented by the vector D can be solved. Therefore, the gen-- eration of a first voltage representing the vector D and of a second voltage representing the vector D and of a third voltage representing the slant range V of the missile from the aircraft (where V =(V +D when the aircraft is at the position O will enable a replica of the position of the simulated missile 0 to be made.

That is, the voltagegrepresenting D may be used to provide a transverse deflection of a cathode-ray beam along a vertical Y-axis on the display screen of the oscilloscope, and the voltage representing the vector D can be used to provide a horizontal Z-axis deflection of the beam. Therefore, the resulting position of the spot corresponding to the beam will correspond to its ordinate position with respect to the Y and Z-axis. Then, the voltage representing the slant range V may be used to deflect a second cathode-ray beam in the oscilloscope to provide range indications of the distance from the aircraft to the missile.

In the manner described above, the actual ordinate and coordinate position of the simulated missile with respect to the-aircraft can be displayed. Moreover, the distance from the aircraft to the simulated missile may also be displayed, these latter indications being correlated with derived radar indications of the range from the aircraft to the actual target. Then, and by correlating these computed and radar-derived indications with the optical record of the target, the point at which the, simu- Q lated missile crosses the path of the target can be determined. Then, and in'the described manner, the miss distance of the simulated missile and the target can be calculated.

The control system of Figure 6 is a schematic and block representation of a typical control that can be used in carrying out the objectives of the present invention. The system is shown merely in block form because each of the individual components per se are known to the art and are procurable on the market. It is believed unnecessary to encumber the present record with the somewhat complicated and involved electronic circuits that are incorporated in the individual units.

Most present-day fighter aircraft include a series of transducers such as those represented as 100, 102, 104, 106, 108 and 110. These transducers are used to sense various aircraft flight conditions, and to generate individual control signal representative of such conditions. The generated control signals are used in the fire control system of the aircraft to introduce error factors that must be compensated by the maneuvering of the aircraft before the proper on-target designation is produced. These aircraft flight conditions, as pointed out previously, may for example be angle of attack, air velocity, yaw, altitude, turbulence, ambient temperature, etc. The various control voltages from these transducers are all fed to a computer component 112. This computer component, and others to be described, may in reality be portions of a single computer. The individual components are represented as such in Figure 6 to clarify the description of the system. The computer component 112 responds to the control signals, and it generates three voltages V V and V,,. These voltages are controlled to be modified in accordance with variations in the transducers, and they are used to provide the'inclinations and p of the path of the simulated missile in Figures and 50. That is, the various aircraft flight conditions are used in the present invention to control the actual inclination of the path of the simulated missile so that it may be properly directed towards the target. In other words, all these various flight conditions are incorporated into the computed path of the missile as factors for which compensation must be made. The first voltage V,,' is made equal to cos the second voltage V is made equal to sin qt, and the third voltage V,," is made equal to sin e; these values being illustrated in Figure 6. It is noted that these voltages are constant for any set of flight conditions of the aircraft, and that the designated angles and are the respective inclinations of the missile path in Figures 5 and 5a.

The three voltages from the computer component 112 are fed to individual ones of three further computer components 114, 116 and 118. The output terminal of an analogue generator 120 is connected to each of these latter computer components. The analogue generator 120 may be constructed in a manner well understood'to the art. The generator 120 may be controlled to generate a voltage which increases with time and which represents the designated speed of the simulated missile. Expressed mathematically, and as shown in Figure 6, the output voltage V from the generator 12% is:

' arm T m L As noted previously, the aircraft is equipped with three gyros, and these are represented as 122, 124 and 126 in Figure 6. The gyros, as noted, are disposed. on mutually perpendicular X, Y and Z-axes, and they are released at the firing point. Three transducers of known construction 128, 13%) and 132 are respectively coupled to the gyros 122, 124 and 126. These transducers develop corresponding control signals Which are indicative of any rotations of the gyros from their settings on release, such rotations being due to the aircraft being maneuvered from the course it held at the firing point 0, The transducers 128, 130 and 132 respectively develop three output voltages V V and V V cos 0 V =sin 0 V =sin 0' (9) A transducer 136 is coupled to the usual air speed pickofi 138 of the aircraft. The latter transducer develops an output voltage V, which is a measure of the actual air speed of the aircraft:

The three output voltages V V and V from the transducers 128, 130 and 132 are introduced to respective ones of a plurality of computer components 142, 144 and 146. The output voltage V from the transducer 136, on the other hand, is applied to each of these computer components. The computer components 142, 144 and 146 develop respective output voltages corresponding to the vectors X Y and Z; of Figures 5 and 5a. These may be represented as follows:

dFf

X; Lcosd (11) Yf-- f sin 0 (12) T an Zf 81110 dt (13) The voltages from the computer components 114, 116 and 178 and from the computer components 142, 144 and 146 are all fed to a computer component 150. The computer component 15% uses these voltages to produce two distinct output voltages corresponding respectively to the vector D and to the vector D of Figures 5 and 5a. This latter computer component also generates a voltage corresponding to the slant range V, of the missile. As noted above, the voltage corresponding to the vector D is used to provide the vertical deflection, and the voltage corresponding to the vector D, is used to provide the horizontal deflection, of the cathode-ray beam in the cathode-ray tube 31. Therefore, the position of the luminous spot on the display screen of the cathode-ray tube 31 is controlled by the voltages corresponding to the vectors D and D The voltage developed by the computer corresponding to the slant range of the missile V, is, as pointed out above, used for ranging purposes. The various 1 1 voltages D D and V, are represented by the following equations:

In the manner described, therefore, control voltages are developed within the attacking aircraft which are It will be noted that all the terms of the Equations 14, 15 and 16 are fed into the computerlSt) by the various mixers. The computer proceeds in known manner to solve these various equations and to provide the required output voltages. The computer 150 may be any appropriate analogue computer, and many are presently known that are capable of performing the required function.

The aircraft also includes a radar unit 200. This unit may be the usual radar of the aircraft or it may be a separate unit incorporated into the system of the invention. An antenna 202 is coupled to the radar unit, and the radar unit is connected to a sweep unit 204. Both the sweep unit 2% and the radar unit 200 are connected to the cathode-ray tube 30.

The sweep unit 204 is also connected to fiducial range marker generating circuit 206, and this circuit is also connected to the cathode-ray tube 30. The marker circuit 206 responds to a pulse from the sweep unit 204 to generate a series of precisely timed impulses for each sweep of the cathode-ray beam in the tube 30. These pulses are used to deflect the beam in the vertical direction at precise positions across the Z-axis on the display screen of the tube 39. This provides markers that may be calibrated to represent certain fixed radar distances, such as .2 of a mile. A suitable circuit for achieving this is described in Principles of Radar, Massachusetts Institute of Technology, Radar School Stall, second edition, published by McGraw-Hill in 1946, at pp. 273.

The elements 2E2, 2th), 2694, 2% and 3t) operate in known manner as a conventional radar system. The radar unit derives echo pulses from the target and feeds these pulses to the tube 30. The cathode-ray beam in the tube 30 is controlled to exhibit an indication corresponding to the echo pulses.

The resulting indications, together with the fiducial range markings, are projected onto the film strip 50 of Figure 4 in the manner described previously in conjunction with that figure. In this manner, the fiducial range indications produce the markings F in Figure 4 and the echo pulses produce the markings B in that figure.

The cathode-ray tube 30 may be of known construction in which a pair of cathode-ray beams are developed, which beams may be independently controlled and are projected onto a common display screen. The output voltage V, from the computer 150 is also introduced to the tube 30, and this latter voltage is used to control the position of the second beam in the tube 30 and to move that beam horizontally across the Z-axis of the display screen as that voltage V increases. The latter control is in accordance with known and well understood control techniques, and it produces indications of the missile ranges and which are projected as the indications A in Figure 4. The radar control and the voltage V are interrelated and calibrated with respect to one another so that the ranges represented by the markings A and B in Figure 4 are on the same scale as represented by the fiducial range markings F.

appropriate to represent the flight path of a simulated missile. These voltages are corrected and correlated to correspond to the actual conditions under which the aircraft is flying at the time the simulated missile is fired, and they also to take into account any subsequent changes in course of the attacking aircraft subsequent to the firing of the missile. As noted, these latter changes affect the position at which the optical images are recorded, so that a correction must be made to the indications of the flight path of the simulated missile. It is evident, however, that the control elfect due to such changes in course of the aircraft could be utilized to effectively control the optical axis of the recording camera to hold it on the target despite such changes in the course of the aircraft. Then, it is unnecessary to provide any compensating corrections in the indications of the flight path of the simulated missile due to the maneuvering of the aircraft;

Many of the components used by the control system illustrated in Figure 6 are standard in most present-day fighter aircraft. Therefore, the present invention introduces relatively few extraneous components to the aircraft in order to provide the simulated missile scoring system.

In the manner described, therefore, the inherently simple system of the present invention is adapted to be installed in a fighter aircraft, and to be used in conjunction with the tire control system of the aircraft and to use its radar. v

The system of the invention provides an accurate and dramatic record, in that it enables a precise and accurate replica to be traced on a photographic film, which replica corresponds exactly to the flight path of a missile fired under the actual indicated conditions at which the simulated missile was released.

The invention enables fire control systems to be evaluated and personnel to be trained under conditions that correspond exactly to the actual firing of a missile at. a target. However, no missile is actually fired and there are not problems of missile costs or of falling missiles in inhabited areas.

The apparatus of the invention is relatively simple in its construction in that it utilizes known and readily available component parts. Moreover, the apparatus is simple to operate and requires no elaborate control oper ations on the part of the aircraft crew.

I claim:

1. A system for displaying on the viewing screen of a cathode-ray tube the path of a simulated missile fired from an aircraft in flight, said system including: first transducer means for generating a control signal representing the speed of the simulated missile; second transducer means for modifying said control signal in accordance with flight conditions of the aircraft at the firing point of the missile; third transducer means for generating control signals representing the speed of the aircraft and the subsequent departures of the aircraft from its course at the firing point; computer means coupled to said transducer means and responsive to said control signals for producing a pair of signals varying respectively 13 in accordance with components of motion of said simulated missile along respective axes transversing the flight path of the aircraft; and means for utilizing such control signals to control the deflection of the cathode-ray beam in said cathode-ray tube over said viewing screen.

2. A system for displaying the path of a simulated missile fired from an aircraft in flight, said system including: first transducer means for developing a signal representing the speed of the simulated missile; second transducer means for developing signals representing flight conditions of the aircraft at the firing point of the missile; means coupled to said first and second transducer means for developing first control signals representing the flight characteristics of the simulated missile; third transducer means for developing a signal representing the speed of the aircraft; fourth transducer means for developing signals representing departures of the aircraft from its course at the firing point; means coupled to said third and fourth transducer means for developing second control signals representing the flight characteristics of the aircraft subsequent to the firing point; and means for utilizing said first and second control signals to obtain an indication of the flight path of said simulated missile.

3. A System for displaying on the viewing screen of a cathode-ray tube the path of a simulated missile fired from an aircraft in flight, said system including: first transducer means for developing a signal representing the speed of the simulated missile; second transducer means for developing signals representing flight conditions of the aircraft at the firing point of the missile; means coupled to said first and second transducer means for developing first control signals representing the flight characteristics of the simulated missile; third transducer means for developing a signal representing the speed of the aircraft; fourth transducer means for developing signals representing departures of the aircraft from its course at the firing point; means coupled to said third and fourth transducer means for developing second control signals representing the flight characteristics of the aircraft subsequent to the firing point; computer means responsive to said first and second control signals for producing a pair of signals varying respectively in accordance with components of motion of said simulated missile along respective mutually perpendicular axes traversing the flight path of the aircraft; and means for utilizing such control signals to control the deflection of the cathode-ray beam in said cathode-ray tube over said viewing screen.

4. A system for indicating the miss distance between a target and a simulated missile fired at the target, said system including: motion picture camera means adapted to be directed at the target to record in successive frames of a film strip optical images showing movement of the target; means for generating signals representing the flight characteristics of the simulated missile; computer means responsive to such signals for producing a pair of signals varying respectively in accordance with components of motion of said simulated missile along respective axes traversing the flight path of the aircraft; means for utilizing such signals to obtain visual indications of the flight path of the simulated missile as viewed from the aircraft; means for directing such visual indications to said film strip to be recorded in successive frames thereof superimposed on the optical images therein; further means for developing signals representing the range of the simulated missile from the aircraft and the range of the target from the aircraft; means for utilizing said last-named signals from said further means to obtain visual indications of the range of the simulated missile 7 from the aircraft and of the range of the target from the aircraft, and means for directing said last-mentioned visual indications to said film strip to be recorded thereon adjacent successive ones of said first-mentioned frames.

5. A system in an aircraft for indicating the miss distance between a target and a simulated missile fired at the target from the aircraft in flight, said system including: motion picture camera means adapted to be directed at the target to record in successive frames of a film strip images showing movements of the target; first transducer means for generating first control signals representing the flight characteristics of the simulated missile; means for utilizing such first control signals to obtain visual indications of the flight path of the simulated missile; second transducer means for generating second control signals representing the speed of the aircraft and the subsequent departures of the aircraft from its course at the firing point of the missile; further means for using said second control signals to modify said first control signals so as to control said visual indications and compensate for such departures of the aircraft; and means for directing the visual indications to the film strip to be recorded in the successive frames thereof superimposed on the optical images therein.

6. The system defined in claim 5 which includes: means for generating signals representing the ranges from the aircraft to the simulated missile and to the target; means for utilizing said last-named signals from said last-named means to obtain visual indications of the ranges of the simulated missile and of the target from the aircraft; and means for directing said last-mentioned visual indications to said film strip to be recorded thereon in successive transverse frames in successive ones of said first mentioned frames.

7. In a system for use in an aircraft to indicate the miss-distance between a target and a simulated missile fired from the aircraft at the target, the combination of: motion picture camera means positioned in the aircraft and adapted to be directed at the target to record in successive frames of a film strip optical images showing the path of the target as viewed from the aircraft; means for developing signals representing the flight path of the simulated missile as viewed from the aircraft; means for utilizing such signals to obtain a visual indication of the flight path of the simulated missile as viewed from the aircraft; means for directing such visual indications to the film strip to be recorded in successive frames thereof superimposed on the optical images therein; further means for deriving a further signal representing the range of the simulated missile from the aircraft; radar means for developing signals representing the range of the target from the aircraft; means for utilizing the further signal from the further means and for utilizing the signals from the radar means to obtain visual range indications of the range of the simulated missile from the aircraft and of the range of the target from the aircraft; and means for directing the visual range indications to the film strip to be recorded thereon adjacent successive ones of the film frames thereof thereby to identify the film frame at which the range of the simulated missle equals the range of the target.

References Cited in the file of this patent UNITED STATES PATENTS 2,705,319 Dauber Mar. 29, 1953 2,710,722 Droz et al. June 14, 1955 2,777,214 Birmingham Jan. 15, 1957 2,843,028 Ward et a1. July 15, 1958 OTHER REFERENCES Electronics (Pub.), vol. 25, issue 10, October 1952, pages 98-401.

Birtley: Computer Simulates Moving Radar Target," Electronics, September 1953, pages 137-139. 

